On 20 Nov 2011, at 21:55, Pat Hayes wrote:
>> it's not unreasonable for a reader to start with the working theory that literals with a datatype IRI that isn't known to denote a datatype are also considered ill-typed.
>
> Not unreasonable, but still wrong. The problem is that when we don't know what the datatype is, the value of the literal really could be anything. In particualr, it could be a perfectly good literal value. So we can't in this case impose the 'not in LV' condition on the value: we just don't know enough to tell. When we do have a datatype and a string which the datatype mapping knows is not allowed, then we can impose the not-in-LV condition, but this is a much more informed state to be in that not even knowing the datatype.
That makes sense to me.
> What I meant was, if unknown means 'not known', then you might come to know it later. Its being not known is labile, because new information might come along. BUt if "unknown" is a classification or a kind of value, then once somehting is "unknown" it has to stay "unknown". Coming to know it later is then actually a kind of contradiction. (This issue comes up acutely in considering three-valued logics, BTW, which I once studied in more depth than I care to remember, a long time ago.)
When I read â€œunknownâ€